But it is also a proposition fully weighted with strategic risk, not least because Santos has no imminent production from the slice of the domestic market he is talking about.

The Santos boss has offered the Northern Territory onshore shale plays as a theatre for developing a sensible version of domestic gas reservation. But Santos has, so far at least, drilled but one well on the potential source of the future domestic gas that Gallagher has generously offered up, on behalf of all current and future drillers, for partial domestic reservation.

"The last thing we need is ... the lack of an ability to sell into free markets to scale up investment," says Kevin Gallagher. David Rowe

The pioneering Santos well that attempted to reveal the quality of the NT's McArthur Basin was called Tanumbirini-1. It was drilled in 2014 and, while it identified much to be excited about, it was not asked to flow gas by the explorers operating the drill.

Indeed, it is Santos' competitor in Gladstone export gas, Origin Energy, that has delivered the nearest we have to a McArthur Basin eureka moment.

So, for the moment at least, Gallagher is talking about other people's gas – and that is never a good way to start on a pathway to conversion that the Santos man says requires broad and firm industry alignment.

The embrace of domestic reservation by someone with industry standing such as Gallagher – no matter how non-binding and highly conditional – represents a profound shift from the free-market philosophy that has guided the intellectual hand of the Australian petroleum industry for nearly three decades.

After delivering an informed and informative appraisal of why the gas industry finds itself with a slippery grip on its community licence, the Santos boss helped open the Australian petroleum industry's annual pow-wow with an invitation to join him in contemplation of how gas reservation might be made palatable.

Gallagher said later that he had never been opposed to reservation and he did not believe it stifled investment. But his peer group has and does.

Now, lest we make the mistake of selectively quoting Santos' paradigm shifter, here is what he told the APPEA conference yesterday.

"We need to sit down and take a fresh look at policy ideas that have broad community support, but to which we have historically been opposed," he said after an idiosyncratic history lesson that claimed success for Western Australia's 30-year-old gas reservation policy.

"If we refuse to engage in a discussion about national interest tests and domestic gas reservation policies, we might find ourselves squabbling over the spoils of defeat," he said.

"Gas users and trade unions have expressed concern that territory gas might simply flow out of Gladstone as LNG, with no benefit for domestic gas users.

"A blanket reservation policy would render development of the NT's shale gas resource uneconomic, since it would prevent the achievement of scale that only an LNG industry can provide to justify the large capital investment required to extract the gas and bring it to market.

"However, industry should be open to discussions with governments, gas users, unions and communities about sensible ways to reserve an agreed portion of NT gas for the domestic market.

"Some will say that this is a retreat by the industry, but it is a necessary step on the journey we need to take to rebuild trust in our industry as part of a longer-term strategy to better engage with the Australian community.

"We need to recognise that politics is the art of the possible. We should want to satisfy the legitimate aspirations of Australians for long-term domestic gas security as part of our social licence for the future development of Australia's enormous resources," he finished.

Now, we have long been a fully signed up member of the no-reservation club. But as new Shell and APPEA chairman Zoe Yujnovich suggested, the old rules no longer hold firm in a world where a cloud of community dissent can so speedily alter perceptions of what is good and bad.

So, let's try and think this through.

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The first point to make is that Gallagher is talking about regulating supply not price. And he is also talking about reservation for the NT, whose government is about to start sending gas that it buys but cannot use to east coast markets.

As well, domestic gas prices increasingly reflect net back export prices. So, given there are no price controls on the reserved gas, the result would be neutral for the producers as long as the volumes demanded were not excessive.

But there is another twist here.

It is my firm view that Santos, Origin and even the federal government hold great hopes that the McArthur shales are likely hosts of big oil as well as big gas. If hope becomes reality, then the place really is the game changer – for companies and national economy alike – that Gallagher suggests it could be.

If there are liquids then the economics of development improve exponentially and an enforced leaching into domestic markets will be easy to swallow. But if the gas is dry then the gas will simply be less attractive to the east coast market because the production and transport costs will be high.

So, if the McArthur shales play their role and deliver to Gallagher's expectations, then this could work out pretty nicely. Mind you, that remains a pretty big if.

First thing yesterday, Santos' biggest individual shareholder, the Shanghai listed ENN Ecologicial Holdings, went into trading halt on its local bourse citing "preliminary agreement" on the share transfer deal that will deliver Harbour upwards of 15 per cent of its Australia target.

ENN owns 10.31 per cent of Santos and it sits in a "strategic relationship" with Santos' original Chinese saviour, private equity firm Hony Partners, which speaks for another 4.8 per cent.

The associated investors have been negotiating with Harbour since April 3 over the terms of an arrangement that will see them flick their combined 15 per cent interest into an unlisted special purpose vehicle that has been created to own those shares.

ENN's notification of a trading suspension that "will not exceed 30 days" noted that management had reached a form of agreement with Harbour on May 14 to make the share exchange.

It is not clear whether discussions with Hony have reached similar preliminary finality, but ENN's announcement confirms that the first great leap on to the Santos register has all but been completed.

The news flow from Shanghai is said to have left Team Harbour both surprised and bemused.

From what we understand, Harbour is seriously close to a stay-or-go decision on its long-flagged bid but that the warning note issued to the market yesterday accurately characterises the weight of doubt over just what its private equity stalker might do.

The Santos statement said in part that the company had "not received a notification of any agreement between Harbour and ENN or any change in the substantial holding in relation to its shares".

There is more to that statement than might appear to the eye.

One of the many consequences of the "strategic relationship" agreement that Santos and its associated Chinese owners forged in June last year is that the oil company is deemed to have a relevant interest in the 15 per cent of its register that is owned by ENN and Hony.

As a result, Santos would need to inform the market if there was any change in the level of ownership that its associates own. Patently then, Santos needs to know whether or not an arrangement that has required ENN's suspension in Shanghai is binding enough to oblige notification to the ASX of a change of a significant shareholding.